The present invention relates to disk brakes and, more particularly, to disk brake calipers for lightweight vehicles such as bicycles.
Due to the superior characteristics of disk brakes with respect to simplicity of design, ease of repair, resistance to fading and long life, it is desirable to mount disk brakes on smaller vehicles such as bicycles. However, a disadvantage with conventional disk brake designs is that the disk brake pads are mounted on solid pistons which are slidably retained within cylindrical cavities formed in the calipers which include return springs that urge the pistons sidewardly to disengage the attached pads with the associated rotor when the cylinders are depressurized. Such structure adds to the overall weight and expense of the bicycle and presents a relatively high profile for a device which is mounted at or on the hub of a bicycle wheel.
Attempts have been made to design a low profile disk brake, such as that disclosed in Campagnolo U.S. Pat. No. 3,971,457. That patent discloses a wheel hub disk brake in which the wheel hub of a bicycle or motorcycle includes an inner, rotating segment attached to the wheel and positioned between two outer, non-rotating segments. The non-rotating segments are urged inwardly by ring pistons to bring ring disks into engagement with corresponding metal disks mounted on the rotating, inner hub to prevent relative rotation of the inner hub with respect to the outer hub segments in order to brake the wheel.
A disadvantage with such structure is that the hub design and ring pistons are relatively complex, requiring high tolerances and expensive castings. Further, while the structure may provide a strong braking force, the amount of metal required is relatively substantial, making such a hub unsuitable for lightweight bicycles. Accordingly, there is a need for a low profile disk brake caliper which is suitable for mounting on a bicycle wheel.